1. Field of the Invention
The invention disclosed herein relates to printing devices, and more particularly to devices for the production of proportionally spaced, high quality justified copy without the use of hyhenation.
2. Description of the Prior Art
Traditionally, proportionally spaced typing has had a fixed format. A given printed character always occupies the same number of horizontal space units although this may vary from character to character (M to I) when typed on a proportionally spaced machine. The characters are somewhat distorted on conventional printers to occupy the entire space allocated to the character. Particularly difficult is the English Script character set and the Arabian Farsi character set, where, to some extent, the characters appear joined together. The problems occur because of the number of combinations of character pairs found in ordinary text. When the spacing between one combination is enhanced, other combinations become poor.
In U.S. Pat. No. 2,742,998 an attempt was made at solving the problem by changing the shapes of so called "lean" letters and placing these "lean" letters in digraphs and trigraphs on the same key face such that the digraph or trigraph would take no more horizontal space than one "fat" small letter, for example "w". This technique, while increasing the number of letters that could be typed on a line, did little to upgrade the aesthetic quality of the type and, in fact, degraded the aesthetic quality because the characters were distorted in order to decrease the space between them. Also, no provision was made for comparably reducing the space between individual characters and the digraphs or trigraphs which formed a part of the same word nor between adjacent digraphs or trigraphs.
A more burdensome problem exists where the printer is to be used for right margin justification of text. It has been common practice, when a word would not fit entirely within a printing line to divide the word on syllable boundaries with a hyphen so that one segment of the word can be accommodated at the end of the line and the other segment accommodated at the head of the following line. This method is used in publication activities to avoid ragged right-edge composition and achieve a high utilization of paper.
Present printing systems provide for the addition of space between words to increase the length of the line to bring its length to the chosen right margin. Exemplary of these kinds of printers are U.S. Pat. Nos. 2,465,657 and 3,530,976. In the U.S. Pat. No. 2,465,657, the text to be justified is printed in a first column as it is keyed by the user. The text must then be rekeyed in a second column while the printer automatically adjusts the interword spacing to justify the right margin. In the U.S. Pat. No. 3,530,976 interword spacing is held to a predetermined minimum space during intial keying. A delta space is then added to each interword space during final playout to obtain right margin justification. However, if the number of interword spaces is too small to fill out the line, hyphenation must be done by the user. This generally results in the use of a dictionary to provide information on syllabication of the word and a corresponding loss of valuable time. Additionally, increases in the interword spacing in a line of printed text causes a corresponding deterioration in the aesthetic quality of the print.